Ward, "this invention can be of no personal use to the man, that he should hide it from the rest of us. There is every reason why he should sell it. Can this unknown be already some dangerous criminal who, thanks to his machine, hopes to defy all pursuit?"

My chief then went on to explain that it had been decided to employ other means in search of the inventor. It was possible after all that he had perished with his machine in some dangerous maneuver. If so, the ruined vehicle might prove almost as valuable and instructive to the mechanical world as the man himself. But since the accident to the schooner "Markel" on Lake Kirdall, no news of him whatever had reached the police.

On this point Mr. Ward did not attempt to hide his disappointment and his anxiety. Anxiety, yes, for it was manifestly becoming more and more difficult for him to fulfill his duty of protecting the public. How could we arrest criminals, if they could flee from justice at such speed over both land and sea? How could we pursue them under the oceans? And when dirigible balloons should also have reached their full perfection, we would even have to chase men through the air! I asked myself if my colleagues and I would not find ourselves some day reduced to utter helplessness? If police officials, become a useless incumbrance, would be definitely discarded by society?

Here, there recurred to me the jesting letter I had received a fortnight before, the letter which threatened my liberty and even my life. I recalled, also, the singular espionage of which I had been the subject. I asked myself if I had better mention these things to Mr. Ward. But they seemed to have absolutely no relation to the matter now in hand. The Great Eyrie affair had been definitely put aside by the government, since an eruption was no longer threatening. And they now wished to employ me upon this newer matter. I waited, then, to mention this letter to my chief at some future time, when it would be not so sore a joke to me.

Mr. Ward again took up our conversation. "We are resolved by some means to establish communication with this inventor. He has disappeared, it is true; but he may reappear at any moment, and in any part of the country. I have chosen you, Strock, to follow him the instant he appears. You must hold yourself ready to leave Washington on the moment. Do not quit your house, except to come here to headquarters each day; notify me, each time by telephone, when you start from home, and report to me personally the moment you arrive here."

"I will follow orders exactly, Mr. Ward," I answered. "But permit me one question. Ought I to act alone, or will it not be better to join with me?"

"That is what I intend," said the chief, interrupting me. "You are to choose two of our men whom you think the best fitted."

"I will do so, Mr. Ward. And now, if some day or other I stand in the presence of our man, what am I to do with him?"

"Above all things, do not lose sight of him. If there is no other way, arrest him. You shall have a warrant."

"A useful precaution, Mr.